   (info "Transforming" (count concepts-tuples) "concept(s) to" format)
   (let [mdb-context (context->metadata-db-context context)
         [t1 concepts] (u/time-execution
-                        (metadata-db/get-concepts mdb-context concepts-tuples allow-missing?))
+                        (doall (metadata-db/get-concepts mdb-context concepts-tuples allow-missing?)))
         [t2 values] (u/time-execution
                       (doall (pmap #(concept->value-map context % format) concepts)))]
     (debug "get-concept-revisions time:" t1

            "tombstone-filter time:" t3
            "concept->value-map time:" t4)
     values)))


(defmethod extract-access-value "application/echo10+xml"
  [concept]
  (let [^String metadata (:metadata concept)]
    ;; This contains check is a performance enhancement. This saves a lot of time versus the regular
    ;; expression below when the metadata is a large string.
    (when (.contains metadata "Restriction")
      (when-let [[_ restriction-flag-str] (re-matches #"(?s).*<RestrictionFlag>(.+)</RestrictionFlag>.*"
                                                      metadata)]
        (Double. ^String restriction-flag-str)))))

(defmethod extract-access-value "application/dif+xml"
  [concept]
